z axis does not touch limit switch



  • A couple of months ago I began to notice that when doing auto home from the menu and before starting a print, the Z axis does not go down completely to activate the limit switch of said axis, which makes the tip of the nozzle remain way above what it should, I have this problem and it is constant and there are very few times in which if it goes down completely and works as it should, until now I have not found useful information about it and I do not have as much experience as to modify something from the printer.
    The printer is from the factory, it does not have any modifications except visual modifications for the cables.



  • My Ender 3 V2 does the same thing, the switch doesnt click but is activated, so the nozzle homes a little bit up. I have to home the printer many times for the switch to work. I also changed the Z axis switch for the X axis switch and worked propperly a few times. Now the X switch and Z switch fail homing triggering before the click sound. It homes but ist not accurate. 😞



  • @BobB The weird thing is that sometimes if you touch it until you click on the switch but other times it just touches it, I still suspect that the switch has a fault and I will replace it to see if that solves it



  • @Kevin_Bogard the video shows the switch lever being touched. Does it always touch? If so I would say there's an issue with the switch itself. It shouldn't activate until the click sound but I've experienced the normally closed contact being intermittent as the plunger moves just before the click. You could change the switch or get a BL touch upgrade. The touch is much more accurate once set up.



  • @BobB In fact, that was my first suspicion about the failure, but connect the printer to the Promterface and run the M119 code to check if they had any problems, but according to the program, everything is fine and answering the question, if you lower the z axis and touch Minimante the end of the race, I leave you a video so you can see what I mean

    https://drive.google.com/file/d/1nOcLFztveqAdcV_lX_Ew8Ffvu5LOXMXe/view?usp=sharing

    That was one of the best attempts, I almost clicked the switch but there are other moments where it does not go down completely that it barely gets to touch it



  • @Kevin_Bogard you didn't answer the part about whether the z carriage makes an attempt to move down. If it doesn't you may have a problem with the z axis switch. If it does I'm thinking perhaps a noise issue randomly triggering the z axis stop. If this is the case try winding the z to the top. You'll likely find after each home request it will move down a random amount before a false trigger.



  • @BobB Yes, I can move the axis by deactivating the motors and returning to the initial position, but when I return to home, it does not touch the limit switch again



  • @Kevin_Bogard So after homing you are able to disable steppers and manually wind the carriage down until it hits the switch? When homing does the carriage move down at all?



  • @BobB the z axis works in a normal way, it does not make any strange noise when going down or going up, and off I can move it without any kind of problem, the only thing I don't understand is that it does not touch the end of the stroke and at the time of printing there is much more above the bed



  • @Kevin_Bogard The z axis would usually keep moving until the switch is activated. Perhaps the carriage is getting caught or stuck on its way down. Does it make a loud noise? After, if you switch the printer off, can you manually rotate the z axis lead screws to lower the carriage onto the switch?


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